Cathode ray tubes (CRT) are widely used as display devices. For example, most conventional television sets incorporate a cathode ray tube. Additionally, most conventional computer monitors also include a cathode ray tube.
A cathode ray tube commonly has a relatively flat broad bottom surface on which the television picture or computer image is displayed. Above the relatively flat display surface, the cathode ray tube narrows to a neck portion in which an electron source is disposed for firing a beam of electrons at the flat display surface. A layer of phosphor on the flat display surface responds to the beam of electrons by emitting light resulting in an image as viewed by the television viewer or computer user.
A common problem with cathode ray tubes is the reflection of ambient light from the display surface which obscures the image or picture being shown on the tube. In order to reduce such reflection or glare, an anti-reflective film is commonly adhered to the display surface of the cathode ray tube.
An exploded view of such a conventional cathode ray tube is illustrated in FIG. 1. As shown in FIG. 1, a heat shrink band (102) is applied around the display surface of the cathode ray tube (106). This band, when tightly fit about the cathode ray tube, provides additional support and strength to the tube in the area around the display surface. Within the heat shrink band (102) in place, the anti-reflective film (101) is adhered over the display surface of the cathode ray tube (106).
Prior to application of the anti-reflective film (101), the display surface of the cathode ray tube (106) is carefully cleaned. After the anti-reflective film (101) is laminated on the display surface of the cathode ray tube (106), the anti-reflective film (101) is carefully inspected for continuous adhesion to the cathode ray tube (106).
FIG. 2 illustrates the display surface of an assembled cathode ray tube. As shown in FIG. 2, the anti-reflective film (101) is framed within the heat shrink band (102). In order to allow for the discharge of static electricity that may accumulate on the anti-reflective film (101) during operation of the cathode ray tube (106), conductive tape (103) electrically connects the anti-reflective film (101) with grounding electrodes (104) on the heat shrink band (102).
The conductive tape (103) is commonly provided near the corners of the display surface of the cathode ray tube as illustrated in FIG. 2. The conductive tape may be made from, for example, copper, and is soldered onto the anti-reflective film.
FIG. 3 illustrates the anti-reflective film (101) without any other components being shown. The size of the conventional anti-reflective film (101) is essentially coextensive with the area framed in the interior of the heat shrink band (102).
While the anti-reflective film (101) substantially improves the ability of the cathode ray tube (106) to display high-quality images, there exists a significant problem. With time, the adhesive between the conventional anti-reflective film (101) and the cathode ray tube (106) begins to fail. Typically, this is initially manifested by pealing of the anti-reflective film (101) away from the display surface of the cathode ray tube (106). This pealing may create shadows or air pockets on the anti-reflective film (101). These features degrade the image being shown on the cathode ray tube (106). Eventually, the reflective film (101) will peal completely away from the cathode ray tube making it further difficult to use the cathode ray tube (106) as a display device.
Consequently, there is a need in the art for an improved anti-reflective film and method of making and applying the same that has an improved durability and is not liable to the pealing commonly observed in conventional anti-reflection coatings on cathode ray tubes.